Preparation of halogenated esters



Patented Aug. 19, 1952 ration of Delaware Atypical reaction of this typeis represented by'the following equation when employing meta dioxanes asthe cyclic acetal.

Ill XRiH H wherein R1, R2, R3, R Rsand Rs are hydrogen, halogen, alkyl,aryl, aralkyLcycloalkyl, alkaryl, haloalkyl 01".fl1kQXY alkyl groups,and X is a halogen atom such as a chlorine, bromine; or iodine atom. .R7is an alkyLaryl, .arallsyl, alkaryl or'halo alkyl radical;

" The halogenated estersso formedmay be used as' 'solvents resin orrubber. plasticizers, and

cl emicalgintermediates, or they may be sub-, jected; to furtherreaction, such as hydrolysis of the halogen atom, saponiiication of theester group, or, dehydrohalogenation to yield related products-such asunsaturated esters, unsaturated alcohols, chlorohydrins or glycols. Inthis way,

compounds which are otherwise diflicult ,to obtain may be prepared bythis novel and useful process.

Thus, according to the present invention,

halogenated esters are prepared from cyclic acetals, suchvas themeta-dioxanes and .dioxolanes. The'qmeta-dioxanes are cyclicacetalspossessing six-membered rings and having the following. general formula;

' yPREPAan'rIoN F HALOGENATED ESTERS 'Erving Arun'dalefwestfield, N. J.,assignor to Standard Oil Development Company, a corpono Drawing.YApplication December '14, 1949, a s jS erialNo.133,006" 1 i 4 Claims(01. 2so 496) wherein R1, R2, R3, R4, R5, and Re are hydrogen, alkyl,aryl, cycloalkyl, aralkyl, or alkaryl radicals, or substitutedderivatives thereof,.such-as haloalkyl, alkoxyalkyl radicals, and thelike.

These meta-dioxanes may be prepared by any of several well knownmethods. One especially good method is by the reaction of two moles ofan adlehyde with one mole of an organic material containing an olefinicbond in the presence of an acidic catalyst for example: I'

. K H R, j.

c/ R: i 0 $0 R3 Illa g R1J=CR 2R5("J=O H where R1, R2, Ram, and R5 havethe same meaning as described above. They can alsobe prepared bythereaction of 1,3 glycols with aldea hydes in the presence of anacetalization catalyst such as H2SO4, toluene sulfonic acid, zincchloride, HCl and the like. The dioxolanes are prepared from 1,2 glycolsin a similar manner.

Examples of the cyclic acetals which can be so prepared and are capableof being converted into halogenated esters by the reaction of thepresentinvention are as follows (the numbering of the atoms composingthe meta-dioxane 'and dioxolane rings is indicated in the followingskeleton 'f ormula) 4,4 dimethyl meta dioxane; 2,4,4,67-tetra'-' methylmeta-dioxane; 4-methy1 meta-dioxan'ej 2,6-diphenyl 4,4 dimethylmeta-dioxane; 4,5f dimethyl meta-dioxane; 4-methyl-4-vinyl metadioxane;4,4,5-trimethyl meta-dioxane; 4-propyl meta-dioxane;2,4,4,5,6-pentamethyl meta 1 dioxane; 4-ethyl-5-methy1 meta-dioxane;4,4.-dimethyl 5 tert-butyl meta-dioxane; 4-methyl, i-neopentylmeta-dioxane; 4-methyl f1 phenyl meta-dioxane; 4,5-cyc1oheXometa-dioxane; 4-

'.pare and so are very useful in this process.

Halogen'ated. gnta-dioxanS which may be used in the process-are4-chloromethyl metadioxane, from allyl chloride and formaldehyde;

4-methyl ,4 chloromethyl meta-dioxane, from-- methallyl chloride andformaldehyde; and 44-,

dimethyl-5-chloro meta-dioxane, from isocrotylj chloride. andformaldehyde; 1

The formation of esters by reaction of the cyclic acetals with organicacid chlorides is conducted in the presence of a catalyst or mixture ofcatalysts of thestypev necessary to effect esterifications. Such catathehalogen-substituted 4 slowly to a stirred and heated mixture of organicacid chloride and catalyst. The reaction in most cases is exothermic sothat subsequent cooling may be necessary in order to maintain thedesired reaction temperature. The product can be washed with water toremove catalyst, neutralized with a weak. alkali togremov'e g'acid,dried' to remove water, and subsequently i vacuum distilled;

ICyclic acetals suitable as starting materials for this process may be.prepared by the condensation of olefins, orother unsaturated compounds,with aldehydes injtheipresence of mineral acids. .It

lysts include sulfuric, hydrochloric, phosphoric,"

chlorsulfom'c and other acids or inorganic halides such asborontriflucride', zinc'chlc'ride, stannic chloride, aluminum chloride,ferric chloride,-cal cium chloride and the "like, and-of these the'in-forganic halides are to bepreferred. Anhydrous zinc chloride'has beenfound to be especially use-.

an; While a reaction does take place in the presence of inorganic acidcatalysts, the yield of desiredhalogenated "ester is usually lower-than' when inorganic halide catalysts are-used.

Mixtures of the above catalysts-may also"'b'e employed; for example,inorganic salts such as zinc. chloride, calcium chloride, zinc sulfate,etc. may he added to mineral acids as auxiliary reaction promoters. Amutual solvent such as carbon tetrachloride or chloroform may be used toprovide, better contact between the reactants-and catalyst. A catalystof such a nature and concentration that it will cause polymerization ofthe reactants and/or of the halogenated ester products' obtained in thisprocess should baavoided.

and'care' should be exercised to chooseacatalyst for obtainin 'opti-mumresults with each partied? larfc'yclic acetal. The amountof. catalystem-J ployedv ranges between 0.05 we Weightpercent based on. thereactantsand usually betwe'enOb to2percent. f

"The acid halides which may be used to react \viththe cyclic acetals andwhich function infthe reactionjboth as esterification andhalogenatio'n,v agents may consist of any acid' halide-containing 2 12carbon atoms, that is, .afiuoride, chloride, bromide or iodide,although, generally the usec'i a chloride or bromide is mostv practical1.since these compounds are by far the most readily available, moststable, and most convenient to one .andseveral atmospheres. The timerange.

within which the reaction is completed generally extends from 0.1 to 16hours.

Thefprocess of the present invention may be.

carried out infeither' a batch or continuous fashionand in either theliquid orvapor phase;

It is.preferred, .however, to add the cyclic acetal is not necessary toisolate the meta-dioxanes; instead. any' water'is removed and theolefin-aldehyde reaction mixtures containing the cyclic .lacetalsreacted directly with the organic acid "halides to produce thehalogenated esters therefromif' 1 In order to obtain maximum yields ofthe preferred halogenated esters, it is desirable toi use betweenone ortwo moles of organic ac-idrhalide for each mole of cyclic acetal. If twomolesvoi acid. halide are employed, there will be produced twodistinct-; halogenated ester PIOdLICtSpWhCSi-Z general structuresare-shown above. Obviously the two esterswillbe formed in equalproportions and will beproduced in direct amounts" to .the amountof'cyclic'acetal decomposed. Halogenated esters which can be produccd'bythe process ofthi invention include lacetoxy-3e chlorobutane, 1 acetoxy3-chloro.-3-.-,methylbutane, 1-benzoxy-3-chloro-3-methylbutane,l-acetoxy-Z-methyl-S-chloropentane, 1 acetoxy 3- chloro-3-phenylpropane,1 acetoxy 3-methy1- 3,4-dichlorobutane, chloromethylacetate,chloromethylbenzoate, l acetoxy-2- chloropropane, 1.-acetoxy-2-chloroethane and the like.

The following examples are given for the pur' 'pose' of illustrating theprocess of this invention:

Example I A mixture of 4 moles of acetyl chloride and 10 grams ofanhydrous zinc chloride was stirred and heated at 50-551 C.' (reflux'temperaturelwhile;

there are addedi2. moles'fof 4,9.l-dimethyl me adioxane over a period ofil/ hours. Thevreactionwa's exothermic. ,At the end of 4 hours 7 waterwas'added'an'd the reaction mixture washed with. a ,5 potassiumcarbonate solution. There appeared to be very little acidity presentin.. the.

aqueous layer indicating substantially complete reactionof the acetylchloride with the metaanalyzed .as follows:

. F 'Ih edretical I 1 for Gt'EiOjCl Pement'GarbwHJ 40.33" 33. 2Percent-Hydrogen- 6. 89 7.4-5 Percent engine. 31.0. 1 32.7

This i impure chloromethyl acetatef I The sec 0nd product boils at46.7-50 C. at 4 mm. and gave the following analysis:

Theoretical m for 0711120101 The analysis indicated this product to be achloroamyl acetate of the structure expected, (1-acetoxy-3-methyl-3-chlorobutane) Both products were obtained insubstantially quantitative yield.

Example II A mixture of 2 moles of isocaproyl chloride and grams ofanhydrous zinc chloride was mixed and heated to 70 C. One mole of4-ethyl-5- methyl meta-dioxane (from pentene-2 and formaldehyde) wasthen added slowly (with stirring) over a period of 1%, hours, thetemperature being maintained between 77-83 C. After the addition of themeta-dioxane was complete, the reaction period was continued for anadditional minutes. The resulting reaction mixture was then cooled to 50C. and water was added slowly. The mixture was stirred briefly andcooled to room temperature. The organic product was washed with a 5%sodium carbonate solution, ether was added, and the ether extract waswashed with water. The ether extract was dried over an anhydrous calciumchloride-sodium sulfate mixture. The dried solution was filtered, theether removed, and the residue subjected to vacuum distillation. Thechloro-hexyl isocaproate product boiled between 76 and 90 C. at 7 m. m.The crude chloroester product analyzed as follows:

The ester structure can be formulated as follows:

CH: O H l H CHsCHz-(E-fi-CHzO C (351111 Some higher boiling material wasalso obtained.

What is claimed is: 1. A process for the preparation of organicchloroesters which comprises reacting 1 mole of meta-dioxane having atleast one alkyl substituent at the 4 position of the ring with two molesof an organic acid chloride in the presence of an organic metalcatalyst, said alkyl substituent having 1 to 5 carbon atoms, andrecovering two chloroester products, one of which .has chlorine attachedto the third carbon atom of an alkyl radical joined by its first carbonatom to oxygen of an ester group.

2. A process for the preparation of organic chloroesters which comprisesreacting 1 mole of a meta-dioxane having at least one alkyl substituentin the 4 position of the ring with two moles of an organic acid chloridein the presence of zinc chloride as a catalyst at temperatures below 150C., said alkyl substituent having 1 to 5 carbon atoms, and recoveringtwo chloroester products, one of which has chlorine attached to thethird carbon atom of an alkyl radical joined at its first carbon atom tooxygen of an ester group and the other being a chloro methyl ester ofthe organic radical in said organic acid chlo- 'ride.

3. A process for the preparation of a chloroamyl acetate andchloro-methyl acetate which comprises reacting one mole of 4,4-dimethylmeta-dioxane with two moles of acetyl chloride at -55 C. in the presenceof zinc chloride as a catalyst.

4. A process for the preparation of chlorohexyl isocaproate whichcomprises reacting one mole of 4-ethyl-5-methyl meta dioxane with twomoles of isocaproyl chloride at approximately 0., in the presence ofzinc chloride as a catalyst.

ERVING ARUNDALE.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,314,454 Manchen et al. Mar. 23,1943 2,377,878 I Gresham June 12, 1945

2. A PROCESS FOR THE PREPARATION OF ORGANIC CHLOROESTERS WHICH COMPRISESREACTING 1 MOLE OF A META-DIOXANE HAVING AT LEAST ONE ALKYL SUBSTITUENTIN THE 4 POSITION OF THE RING WITH TWO MOLES OF AN ORGANIC ACID CHLORIDEIN THE PRESENCE OF ZINC CHLORIDE AS A CATALYST AT TEMPERATURES BELOW150* C., AND ALKYL SUBSTITUENT HAVING 1 TO 5 CARBON ATOMS, ANDRECOVERING TWO CHLOROESTER PRODUCTS, ONE OF WHICH HAS CHLORINE ATTACHEDTO THE THIRD CARBON ATOM OF AN ALKYL RADICAL JOINED AT ITS FIRST CARBONATOM TO OXYGEN OF AN ESTER GROUP AND THE OTHER BEING A CHLORO METHYLESTER OF THE ORGANIC RADICAL IN SAID ORGANIC ACID CHLORIDE.